The present disclosure relates to substrate sensing devices, and more particularly, to an optical device and method for characterizing a substrate.
It is well known that the quality of a substrate, such as paper, can vary from batch to batch, which can have a significant impact on image quality (“IQ”) performance of print jobs. This variation usually occurs when paper is manufactured. Even substrates of the same type, whether they are glossy, recycled, copy, or formal substrates, may vary in quality from batch to batch. One of the types of variations in which batches may differ is their electrical properties. It is known that the electrical properties of a substrate play a major role in image quality performance, since an electric field is utilized to transfer toner to substrate. Thus, the electrical properties affect the IQ performance of a print job, which in turn, increases image mottle and/or spots, more specifically, half-tone mottle.
In the business arena, a customer usually reports a print quality problem to a service technician. The service technician then examines the configuration of a printing machine, the condition and quality of the imaging components of the printing machine, and the type and/or brand of paper being used. The service technician evaluates the problem and presents the results to the customer. It would be useful and beneficial to have a device that can characterize the quality of paper and determine whether the substrate has caused or will cause any deterioration in print quality and/or image quality.
It is known in the prior art, particularly, in pending patent application reference: U.S. patent application Ser. No. 12/266,125; filed Nov. 6, 2008; Wayman et al.; titled “Substrate Characterization Device and Method For Characterizing a Substrate,” now U.S. Pat. No. 7,855,565, issued Dec. 21, 2010, assigned to the same assignee as the present invention, to use electrical capacitance measurements to identify paper image quality. However, there are limitations on the use and versatility of this type of measurement. Under certain conditions, the optical properties of the substrates, rather than the electrical properties can affect the image quality in a more significant way. It has been discovered that optical measurement techniques provide favorable/complementary options to define paper quality and image quality in a printing system.